Canonical has announced that they are going to start delivering newer editions of Firefox to the users who are using Ubuntu 10.04 and 10.10.
Ubuntu developers said in a mailing list:
Starting on January 17, Ubuntu 10.04 LTS and Ubuntu 10.10 users will be migrated to the latest Firefox version, and will track the rapid releases going forward, as is currently done in newer releases of Ubuntu. This will enable users to get the numerous improvements offered by new Firefox versions.
Add-ons that were previously in the Ubuntu archive, such as flashblock or webdeveloper, will be automatically migrated to reside in your user profile so that they may be updated through the regular update process using addons.mozilla.org. This is necessary to ensure that you automatically get a working version of these addons, if one is available, when a new version of Firefox is released.
As Firefox will be updated to a new version every 6 weeks, the browsing experience might change slightly with each update.
Ubuntu users have nothing to do on their part. These changes would be made on the server side and they would get the updates automatically.